Starting valve for compound engines



(No Model.) 7

W. B. YEO. STARTING VALVE FOR COMPOUND ENGINES. N0. 449,457.

Patented Mar. 81, 1891.

UNITED STATES PATENT OFFICE.

\VILLIAM B. YEO, OF MANCHESTER, ENGLAND.

STARTING-VALVE FOR COMPOUND ENGINES.

SPECIFICATION forming part of Letters Patent No. 449,457, dated March31, 1891.

Application filed October 28, 1890. Serial No. 369,601. (No model.)Patented in England December 31, 1889, No. 20,910.

To aZZ whom it may concern.-

Be it known that I, WILLIAM HEATER YEo, a citizen of England, residingat Herbert Street, Moss Lane East, Manchester, in the county ofLancaster, England, have invented a new and useful Starting-Valve forOompound Engines, (for which I have obtained Letters Patentin GreatBritain, dated December 31, 1889, No. 20,910,) of which the following isaspecification.

Vt hen it is desired to start a compound steam-engine, it may be thatthe piston of the high-pressure cylinder is near the extreme of itsstroke when its crank is 011 a dead-center, or is in such a positionthat the high-pressuresteam supply is cut off, and it may also be thatthe reservoir for supplying the low-pressure cylinder with exhaust fromthe high-pressure cylinder does not contain steam at sufficient pressureto move the low-pressure piston. In order to provide for starting'uudersuch circumstances, compound engines are usually furnished with a cookor valve, by which steam from the boiler can be admitted into the reservoir, so as to give pressure sufficient for starting the low-pressurepiston. The sudden inflow of high-pressure steam is apt to produceviolent shocks, the valves are liable to be violently closed by theexhaust-steam from the high-pressure cylinder, and when the engine islightly loaded they are often subject to a hammering action, by whichthey are broken, and the fragments may occasion great damage in thevalve chests and cylinders.

My invention has for its object to avoid these evils by a constructionof starting-valve such as I shall explain, referring to the accompanyingdrawings.

Figure 1 is a section of starting-valve according to my invention in thecondition which it has when the engine is working or when it is stopped.Fig. 2 shows its condition when it has been moved to admit steam to thereservoir at the starting of the engine.

The valve-box is fixed so as to have a passage A in communication withthe pipe supplying the high-pressure valve-chest, a passage Bincommunication with the high-pressure exhaust, and a passage D leading tothe low-pressure valve-chest, so that the interior of the valve-boxforms part of the intermediate reservoir supplying the low-pressurecylinder with exhaust-steam from the h i gh-pressure cylinder. Thevalve-rod K has a part L of smaller diameter projecting through thecover, or it might be through a packed stuffing-box in the cover, andunder the cover there is a passage P into the valve-box. On the rod isfixed a piston R, having a long boss 0, which is larger in diameter thanthe rod K, and has a small groove or several sm all grooves out along itso far as to extend, when the valve is closed, as shown in Fig. 1, intothe cylindrical cavity in which the piston R is fitted to work, allowingfree escape of water of condensation. This cavity has a port E openinginto the valve-box, a passage H opening to the outer air, and a smallbranch passage G into H, also a communicating port F, having its monthsabout as far apart as the depth of the piston R, and a small branchpassage 0 into F. On the valve-rod K there may also be fixed, as shown,a valve M, fitted to seat on the mouth of the passage B. If, however,the grooved boss C of the piston R be made of such area that thepressure of the steam in the valve-box-that is to say, the exhauststeamfrom the high-pressure cylinder-acting on it is sufficient to overcomethe pressure of the atmosphere on the area of L and that of thehighpressure steam on the annular area of K, then the valve N may bedispensed with.

The valve operates in the following manner: For the purpose of startingthe engine the high pressure steam supply valve is opened, admittingsteam to the passage A. The pressure in the body of the valve-box and inthe passages B and D being at this time low the pressure on the annulararea of the rod K forces it into the position shown in Fig. 2, so thatsteam can pass "freely from A to P into the valve-box and by the passageD to the low-pressure cylinder. In this action the valve M may be ofadvantage, because by closing B it prevents steam from the valve-boxpassing to the high-pressu re cylinder. vVhen the valve-rod first beginsto move, the piston R does not operate as a check, because air or steamcan pass freely from under the piston by the port E and the grooves ofO, and air can enter above the piston by the passages H and G; but asthe piston R descends, closing the port E and taking the grooves of Cbeyond the bottom of the cylindrical cavity, the only escape from belowthe piston being by the small passage 0, the piston is so much retardedin its descent that the opening to P and the closing of M are gradual.Again, when after certain movement of the engine exhaust steam comesinto the valve-box by the passage B,the valve-rod is forced back to theposition shown in Fig. 1,but with retardation due to the partialcushioning of the piston R as it ascends after covering the lower mouthof H, when the only escape is by the small passage G.

Having thus described the nature of this invention and the best means Iknow of carrying the same into practical eftect,l claim In astarting-valve for compound engines, the combination of the shoulderedvalve-rod K L with the passages A P, the piston R, its grooved boss (I,and the ports and passages E F 0 11 G, arranged and operatingsubstantially as and for the purposes set forth.

In testimony whereof I have signed my name to this specification, in thepresence of two subscribing witnesses, this 13th day of 25 October, A.D. 1890.

W. B. 'YEO.

Vitnesses:

OHAs. EDWD. WALKER,

Brookfield, Ger-ton, llfcmcheszfer.

O. H. ScHoBELT,

Chorlton-cumHardy, fllanchester.

